U.S. Pat. Nos. 1,542,116; 3,675,670; 3,722,556; 3,897,807; 3,906,995; 3,989,059; 4,002,192; and 4,007,766 disclose the use of interconnected railway tank cars used to transport large quantities of liquid lading, particularly liquid petroleum, from place to place.
In these patents, interconnected tank cars are loaded and unloaded simultaneously by connecting a loading or unloading conduit to one end car and sequentially loading or unloading the remaining cars. This construction is expensive in requiring connections between adjacent cars, valves at each end of the cars, and controls for opening and closing these valves.